Biosurfactant production from pseudomonas aeruginosa SP 4 using sequencing batch reactors

Abstract

Biosurfactant production in two identical units of sequencing batch reactors (SBRs) was investigate by using a crude oil-contaminated soil isolated Pseudomanas aeruginosa SP 4. The SBR units, having a working and draining volume of 1,500 and 500 ml, respectively, were operated at a constant temperature of 37C under aseptic conditions. The sedimentation, decanting, and feeding step used for all experiments were 50, 5, and 5 min, respectively. Biosurfactant production was studied with palm oil being used as a carbon source and fish steaming waste or mineral medium being used as a nutrient source for growing Pseudomonas aeruginosa SP 4. Effect of nutrient sources, oil loading rates, and cycle times on surface tension reduction, and COD and oil removal were investigated. Among the two nutrient sources, the mineral medium gave the highest reduction of surface tension at an oil loading rate of 2 kg/m3 d. An oil loading rate of 2 kg/m3d with the mineral medium provided the effective surface tension reduction of 28.1/N/m, corresponding to a COD removal of 88% and an oil removal of 94%. From aeration time profile during a steady state cycle, a minimum surface tension was reached at aeration time in the range of 6 to 10 h. In comparing the biosurfactant production with 1-d cycle and 3-d cycle under the same extent of oil concentration (0.6% w/v), the highest surface tension reduction obtained was 58% with 1-d cycle.